SHIPWORMS OF THE PHILIPPINE ISLANDS BARTSCH 553 



cavity behind it. It terminates dorsally in a strengthened cord 

 which separates the expanded portion conspicuously from the nar- 

 rowed dorsal border that extends to the umbone. The inside, like 

 the outside, is marked by concentric corrugations. A strong broad 

 blade extends from under the heavy umbone ventrally. It is broken 

 so that we can not tell the limit of its extent. 



The type (Cat. No. 312933, U.S.N. M.) was collected by the United 

 States Bureau of Fisheries Steamer Albatross Philippine Expedition, 

 from a piece of wood dredged at station 5294, in 244 fathoms on sand 

 and pebble bottom, bottom temperature 48.4°, off Escarceo point. 

 Northern Mindoro. No pallets were found. We are therefore unable 

 to assign a definite systematic position to this species. Its shell char- 

 acters distinguished it from any of the other known forms, and we 

 add it for completeness of record. The type measures: Height, 3.8 

 mm. (it should be here stated that the ventral portion of the valve 

 is broken — a complete specimen would probably measure 4.2 mm.) ; 

 length, 5 mm.; diameter of single valve, 2.4 mm. 



? TEREDO (subgenus?) LUZONENSIS, new species 

 LUZON SHIPWORM 



Plate 55, figs. 2, 6; plate 57, fig. 2 



Shell moderately large, flesh colored with a pinkish flush, the 

 anterior area with a sinus that is bordered with a strong callus which 

 is reflected over part of the anterior area. From the edge of the cal- 

 lus the denticulated ridges spread fan-shaped posteriorly. They are 

 closely approximated at the anterior edge, and the early ones are 

 about twice as far apart as the ridges at their posterior termination, 

 while the later are separated by spaces no wider than the ridges. 

 These ridges are finely denticulated at their free border. Fifty-nine 

 of these are present in the type. The junction of the anterior and 

 posterior median area forms an even curve. The anterior portion 

 of the median area is marked by rather strong dental ridges which 

 are separated by very deep, narrow grooves. Of these ridges 32 are 

 present in a line projected across this area from the ventral border 

 of the anterior part. The denticles borne on these ridges are doubly 

 cusped and where they have been eroded they leave a basal area 

 which is separated into a wider anterior portion and a narrower 

 posterior raised line. The middle portion of the median part con- 

 sists of an anterior convex portion which is crossed by the continua- 

 tions of the denticular ridges which are reflected across it in an open 

 arc but do not bear denticles here, and a slightly concave posterior 

 portion about as wide as the anterior which is crossed by feebler 

 continuations of these lines with finer elements between them. The 

 posterior median part is considerably wider than the anterior and 

 middle portion of the median part, and is marked by fine curved 



